For many chronic inflammatory diseases, antigen-specific immune responses are causative of inflammation and/or dysfunction of a target organ (autoimmune thyroiditis, with of inflammation and/or dysfunction of a target organ (autoimmune thyroiditis, with thyroglobulin; myasthenia gravis, with acetylcholine receptor; post-vaccination encephalomyelitis with myelin basic protein). Given that most of these human disorders are spontaneous and thus unpredictable in onset, animal models have been crucial in working out their basic pathophysiology. For the chronic inflammatory bowel diseases (ulcerative colitis, Crohn's disease) affecting up to 30/100,000 population, epithelium-specific immune responses have been described after disease onset in research studies for over two decades, but there has been no animal model for testing their role in induction or maintenance of tissue injury. The New World monkey, S. oedipus (or cotton-top tamarin), as a recently described primate with a spontaneous chronic colitis, is of considerable interest because (a) animals can be studied prior to lesion onset and serial observations can be made on mucosal histology as well as on immune phenomena; (b) clinically, they resemble the human disease in several ways, including response to therapy (see Background); and (c) antigen-specific immune phenomena, parallel to those in human chronic ulcerative colitis, have been specific immune phenomena, parallel to those in human chronic ulcerative colitis, have been recently described. These include serum immunoglobulin specific for epithelial glycoproteins (designated epithelial cell-associated components, ECAC), up to 18 mug Ig/ml; determinants on their intestinal epithelium reactive with ECAC-specific monoclonal antibodies by immunofluorescence; cytotoxicity against ECAC-labeled targets (using tamarin immunoglobulin and normal mononuclear cells); and Ig binding for one fraction (P1) of macromolecules in ECAC. The long-term objectives of this proposal is to define the role of anti-epithelial glycoprotein- specific immune responses for gut tissue injury occurring in this animal model of spontaneous colitis. Specific aims, then, will be to determine: (1) in what way anti-epithelialglycoprotein immune responses in the CTT are similar to responses in classical autoimmune disease; (2) which macromolecules on human intestinal epithelial cells, derived from stable and established cell lines, bind immunoglobulin from tamarins with spontaneous colitis; and (3) what are the characteristics of T lymphocyte reactivity to intestinal epithelial glycoproteins in the tamarin, particularly with respect to location (gut-associated mesenteric LN versus popliteal LN or spleen); the major T lymphocyte subset involved (CD4 versus CD8); the precise macromolecular in ECAC recognized by CTT T-lymphocytes; and ability to carry out ECAC-specific lysis of labeled target cells. The work proposed is highly important in that (a) a sizeable proportion of the experiments performed will be with immunoglobulin derived from a described model of human disease, and (b) better therapy for these disorders in humans will likely be developed when the role of epithelium-specific immune responses, long described in these diseases, is better understood. Experimental methodology will include: techniques for quantitating ECAC- specific antibody (ELISA; Chromium release assay, immunoblotting); techniques for epitope mapping radiolabeling, radioimmune inhibition binding); sterile cell culture techniques for CaCo-2 and T84 cells as well as for the cytotoxicity assay; and 3H-thymidine proliferation assay to define antigen-specific T lymphocytes after enrichment/depletion of T-cell subsets by monoclonal antibody panning as monitored by FACS.